1. Field of the Invention
The present invention concerns a radio communication antenna fitted with a radome and a method of assembling this kind of radio communication antenna fitted with a radome.
2. Description of the Prior Art
An antenna 10 (FIG. 1a) may comprise a main reflector 12 having a concave side the shape of a paraboloid of revolution about an axis 14 of symmetry of the antenna 10, for example, and a feeder device 16 transmitting the electromagnetic waves transmitted or received by the antenna 10.
To improve the performance of an antenna 10 of this kind, it is known to provide the latter with a cylindrical wall 17, hereinafter called the screen 17. This kind of screen 17 in particular limits lateral radiation from the antenna 10 and thereby improves its performance.
The presence of the screen 17 increases the windage of the antenna 10 and the risk of accumulation of elements such as water, dust or snow in the antenna 10. Also, it is known to fit the screen 17 a radome 18 that has a plane protective surface 19 partitioning the space defined by the reflector 12 and the screen 17 from elements external to the antenna.
The radome 18 consists of a flexible material, for example canvas, which has the advantage of requiring a limited production cost, of having a small overall size when packaged prior to its installation on the antenna—because the radome can be fully or partly folded before it is used—and of being sufficiently transparent to the waves transmitted by the antenna over a bandwidth covering different radio communication applications so that the same canvas may be used to fabricate different radomes for different antennas.
However, the presence of the protective surface 19 of the radome 18 facing the reflector 12 may reduce the performance of the antenna 10. Considering a transmit antenna 10, for example, it is apparent that waves reflected by the protective surface 19 disturb the operation of the antenna 10, these reflected waves being represented by arrows in FIGS. 1a, 1b and 1c. 
To limit this disturbance, it is known to incline the protective surface 19 of a radome 18s relative to the axis 14 of the antenna, as shown in FIG. 1b. This inclination being known as the ‘tilt’, an antenna having a radome the plane whereof is inclined in this way is referred to as a tilted radome hereinafter.
In a tilted antenna, a phase shift is introduced between the reflected waves such that the disturbances generated by the reflected waves cannot be added to each other and the average noise caused by these reflected waves is reduced compared to a non-tilted antenna.
However, a flexible and tilted radome 18s of this kind has drawbacks linked to a relative fragility and to the equipments necessary for assembling it to the screen 17, in particular for tensioning it and maintaining it tensioned with the aid of self-tensioning members such as springs—not shown.
Finally, a tilted flexible radome 18s is asymmetrical with respect to the axis 14 of the antenna. It is then necessary to take into account a specific orientation of the flexible radome 18s when assembling it to the screen 17 and when assembling the screen 17, fitted with the radome 18s to the antenna, this specific orientation being liable to generate assembly errors.
This is why rigid radomes like the rigid radome 18r from FIG. 1c have been developed, this rigid radome 18r having a protective surface 19 that is symmetrical with respect to the axis 14 of the antenna.
Thus a rigid radome 18r of this kind may be fitted to a screen without considering the problem of the orientation of the radome relative to the axis of the antenna.
Moreover, using rigid radomes makes it easy to envisage the use of radomes that are concave or convex relative to the internal cavity of the antenna, such shapes possibly being desirable in particular to reduce the windage of the antenna.
Moreover, these rigid radomes have a high resistance to external elements such as rain, wind or snow.